1. Field of the Invention
This invention relates in general to rescue ladder devices and, more particularly, to a ladder designed to be deployed from a helicopter and rapidly detached therefrom in case of entanglement or other emergencies.
2. Description of the Prior Art
Easily maneuverable aircraft such as helicopters and small planes often play a critical role in civilian and military rescue operations, especially in locations which are not easily accessible to conventional land or sea vehicles. Typically, rescue aircraft are outfitted with lightweight ladders which can be rolled up and easily stored in the aircraft. When needed, a ladder may be removed from its place of storage and secured near the aircraft door by hooking, tying or otherwise securing a rope or fabric attachment portion of the ladder to a pair of D-rings located in recessed portions of the aircraft floor.
The prior art ladder devices have suffered from a number of drawbacks. One problem has been that the ladders, which typically consist of sidepieces made from rope or nylon webbing and rungs made from wood or aluminum, are too lightweight. While lightness is generally considered an advantage in terms of convenience of storage and portability and the like, it becomes a disadvantage when it comes to rapidly deploying the ladder from the aircraft, because a light ladder tends to drop more slowly than a heavy ladder, and to sway in response to wind and air currents, and could even become entangled with the aircraft. Even under ideal conditions, the few seconds which could be lost as a result of a slow and swaying deployment of the ladder may well be critical in an emergency situation.
Another problem associated with conventional aircraft rescue ladders has been that, because the attachment portion of the ladder extends flatly over the vehicle floor, the top rung of the ladder lies directly on the floor, and thus cannot be effectively grasped or grabbed by a climber on the rungs below. This can result in the climber losing his or her balance or greatly slowing his or her entry into the aircraft. In the past, aircraft personnel have attempted to alleviate this problem by placing planks of wood underneath the ends of the top rung in order to vertically offset the rung from the aircraft floor, making it easier to grab. This practice can be quite dangerous, however, because should the planks become dislodged from underneath the rung, they could easily fly about inside the aricraft or fall out of the aircraft and strike bystanders below. In addition, the planks of wood can be cumbersome to store in an aircraft already filled with rescue and other equipment. Furthermore, the process of placing the planks under the ladder is time-consuming and wasteful.
Still another problem associated with aircraft ladders is that they have been known to become entangled in trees or other obstructions, thus preventing the aircraft from making a swift getaway. Consequently, it is necessary to detach the ladder from the aircraft. In combat situations or disaster situations such as fires, the time involved in releasing the ladder by unhooking or untying the attachment portion from the D-rings in the aircraft simply cannot be afforded. Thus, the most common solution in the past has been to simply chop off the attachment portion with a hatchet or ax. Even this practice may be too slow, however, if the ax is not swung with sufficient force. In addition, the ax is a difficult and rather dangerous piece of equipment to handle, particularly in a moving aircraft.
Therefore, a need exists for a new and improved aircraft rescue ladder which overcomes some of the problems and shortcomings of the prior art.